According to the proposal RP-060846 (which is a proposed WID for 64QAM for high speed downlink package access (HSDPA)) of the 3rd generation partnership project (3GPP), a new higher order modulation scheme, such as 64 quadrature amplitude modulation (64QAM), will be added in the HSPA+ downlink. However, the current 3GPP Specs have not defined how to add 64QAM into the new Specs.
According to the section 4.5.6 in 3GPP TS 25.212 V7.3.0, a physical layer channel coding module of a base station (referred to as Node B hereinafter) needs to interleave the data come from the physical channel segment part. However, the current bit interleaving module supports only quadrature phase shift keying modulation (QPSK) and 16 quadrature amplitude modulation (16QAM). A method for bit interleaving for QPSK and 16QAM in prior art is provided in FIG. 1.
In order to completely support 64QAM technology in the HSPA+ system and be compatible with existing HSDPA technology, there is a need for a new method for bit interleaving. The HSPA+ system can support well higher order modulation technology such as 64QAM and be fully compatible with the existing system using the method.